The present invention relates to a buckle having a locking structure for watch bands.
As shown in FIGS. 1a and 1b, a known buckle for connecting a pair of watch bands 10 and 12 comprises an engaging member 1 secured to the band 12 by a clamping member 7 at a desired position, a clasping member 2 rotatably connected to an end of the band 10, and a hook 3 also rotatably attached to the end of the band 10. Other ends of both bands 10 and 12 are connected to a watch W. As shown in FIG. 1b, the buckle is coupled in such a manner that the hook 3 is engaged with an engaging pin 5 provided in the engaging member 1. Then, a grasping end 4 of the clasping member 2 is engaged with another engaging pin 6 over the hook 3 as shown in FIG. 1c.
However, since the parts of the buckle were mass-produced, it was difficult to manufacture the parts without defects. Accordingly, the buckle became incidentally disengaged.
In order to eliminate such a disadvantage, a buckle having an additional locking structure was developed and disclosed in UK Pat. No. 2038917, in which a holding member is pivotally mounted on side frames of an engaging member and a clasping member engaged with the engaging member is locked by the holding member. However, such a holding member can catch things during handling to cause the disengagement of the buckle.
FIG. 2 shows another conventional buckle disclosed in Japanese Utility Model Publication No. 58-3538. In this buckle, an engaging member 13 having a rectangular recess 13a is secured to one of the watch bands 14 and another engaging member 15 having a rectangular connecting projection 15a to be engaged with the recess 13a is secured to the other band 16. A connecting rod 17 having a spring 18 is provided in the engaging member 13 to be inserted into a hole 15b formed in the connecting projection 15a. In order to couple the buckle, connecting projection 15a of the engaging member 15 is engaged with the recess 13a of the engaging member 13 and the end of the connecting rod 17 is engaged with the hole 15b by the spring 18, so that a secure engagement of the buckle can be established. In order to disengage the buckle, a button 17a of the connecting rod 17 is manually pulled.
However, such a buckle is easily disengaged by movement such as hard exercise, because of the slight engagement of rod 17 with the hole 15b. This slight engagement is caused by structural requirements and operability of the buckle.